// $Id: DisseminationUpdate.nc,v 1.6 2010-06-29 22:07:47 scipio Exp $
/*
 * Copyright (c) 2006 Stanford University. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the
 *   distribution.
 * - Neither the name of the copyright holder nor the names of
 *   its contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * Update a network shared (disseminated) value. Updates are assured
 * to be eventually consistent across a connected network. If multiple
 * nodes update a value simultaneously, then nodes within the network
 * will see a series of one or more updates, the last update will
 * be the same for all nodes. Components that need to use the
 * variable should use the DisseminationValue interface.
 *
 * @author Philip Levis
 * @author Gilman Tolle
 * @date   January 7 2006
 */ 



interface DisseminationUpdate<t> {
  /**
   * Update the variable to a new value. This changes the local copy
   * and begins to disseminate the new value throughout the network.
   * As other nodes may have also changed the variable, it is possible
   * that an update may not 'stick,' but will instead be overwritten by
   * a separate update.
   *
   * @param newVal A pointer to the new value. The memory pointed to
   * by newVal is copied out, so newVal can be reclaimed when
   * <tt>change</tt> returns.
   */
  command void change(t* ONE newVal);
}
